As Fernandez is a senator, Congress would first have to vote to strip her of parliamentary immunity for an arrest to occur. The judge, Claudio Bonadio, also indicted and ordered house arrest for Fernandez's Foreign Minister Hector Timerman, the 491-page ruling said. Fernandez and Timerman have previously denied wrongdoing.

While removing immunity from congressional officials is rare in Argentina, Congress voted on Oct. 25 to do so for Fernandez's former planning minister, Julio De Vido, and he was arrested the same day. De Vido is accused of fraud and corruption, which he denies.

Cases involving Fernandez and her allies have picked up, with several high profile arrests and indictments in recent months, after Mauricio Macri, the centre-right mayor of Buenos Aires, was elected president in late 2015. Fernandez has high rejection rates in Argentina and left office just a few months before Congress in neighbouring Brazil impeached another leftist female leader, Dilma Rousseff.

Argentine prosecutor Alberto Nisman was found mysteriously dead one day before he was to present evidence in the 1994 car-bomb attack on Jews in Buenos Aires.
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Earlier on Thursday, two lower level allies of Fernandez were arrested based on the same ruling from Bonadio: Carlos Zannini, a legal adviser, and Luis D'Elia, the leader of a group of protesters allied with her government.

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Zannini's lawyer, Alejandro Baldin, told local media the detention of his client was "arbitrary, illegal and ran over constitutional and individual rights," after leaving a police station in Rio Gallegos, where Zannini is held.

Prosecutor meets untimely end

D'Elia's lawyer, Adrian Albor, told radio Del Plata that Bonadio had no respect for the law, rights, justice. "They are coming for everyone in the previous government."

Former President Cristina Fernandez (centre) is seen here with Julio Grondona, president of the Argentine Football Association (AFA) (left) and soccer star Diego Maradona (right).
Natacha Pisarenko

The death was classified as a suicide, though an official investigating the case has said the shooting appeared to be a homicide. Nisman's body was discovered hours before he was to brief Congress on the bombing of the centre.

Nisman said Fernandez worked behind the scenes to clear Iran and normalise relations to clinch a grains-for-oil deal with Tehran.

Bonadio wrote in his ruling that evidence in the case showed Iran, with the help of Argentine citizens, had appeared to achieve its goal of avoiding being declared a "terrorist" state by Argentina.

Up to 25 years in prison

The crime of treason is punishable by 10 to 25 years in prison, Argentina's maximum sentence. The next step would be an oral trial and sentences can be appealed on first instance, which could be a long process.

Macri's leader in the Senate, Federico Pinedo, said on Twitter Congress would analyse the request to strip immunity "with sincerity and responsibility."

Argentina's legislature has entered a period of judicial recess until March but can be convened for urgent matters.

Macri's coalition performed better than expected in Oct. 22 mid-term elections, gaining seats in Congress. Fernandez, a leftist populist who governed from 2007 to 2015, finished second to a Macri ally in a Senate race in Buenos Aires province but won a seat under Argentina's list system.

She was also indicted in late 2016 on charges she ran a corruption scheme with her public works secretary. Fernandez has admitted there may have been corruption in her government but personally denies wrongdoing.